Synaptic plasticity plays a significant role in learning, memory, and CNS development. The tyrosine kinase focal adhesion kinase (FAK) acts as a regulator of neurite outgrowth mediated by phosphoinositide-linked receptors. Elucidation of the mechanism by which these receptors signal to FAK may aid in understanding the pathways underlying synaptic plasticity. The proposed research focuses on the role of inositol lipids in regulating m3 muscarinic receptor (mAChR) signaling to FAK. Specific Aim 1: To determine if mAChR signaling to FAK is attenuated by blockade of inositol lipid synthesis via overexpression of a dominant-negative mutant or phosphatidylinositol 4-kinase (P14K). The effects of a dominant-negative mutant of PI4Kbeta on mAChR signaling to FAK will be assessed in stably transfected SH-SY5Y neuroblastoma cells by analysis of FAK phosphorylation and in vitro kinase assays of FAK catalytic activity. Specific Aim 2: To evaluate if inositol lipids indirectly regulate mAChR signaling to FAK via effects on the actin cytoskeleton. The effects of phosphoinositide depletion on agonist-induced cytoskeletal remodeling and actin uncapping will be assessed by immunocytochemical analysis of F-actin redistribution and co-immununoprecipitation assays of actin/gelsolin complexes, respectively.